This invention relates generally to the separation of particles and substances from a fluid and more particularly to an apparatus using electrokinetic phenomena in commercial applications for extracting known substances from a fluid or for purifying substances by removal of certain materials.
Charged particles and substances suspended or dissolved in a fluid can be made to move under the influence of an electrical field, one such phenomenon being known as electrophoresis. The speed of movement of a charged particle or substance in an electrokinetic medium in a given electric field, which speed is known as its phoretic speed, is generally dependent on the particle's mass, size, and magnitude of electrical charge. These qualities are specific to each particle and substance as it relates to a specific electrochemical environment. Electrophoresis is well-known and widely used in separation and analysis of compounds present in a fluid. However, the existing art is primarily related to laboratory research and testing, for example, in medical and chemical analysis, and is not applied to commercial quantities of materials. In the existing laboratory art, an electrophoretic element or column generally is a strip or column of wet paper, silica powder or a hydrogel, the column being loaded with a fluid which is to be analyzed for the presence of particular particles and substances. The charged particles and substances may include ions, molecules, compounds, polypeptides, blood cells, etcetera. In the following description, the word "particle" is intended to denote any such material.
When a DC voltage is applied at opposite ends of an electrophoretic element, an electric current flows therethrough. An electrical field is created which causes charged particles in the fluid to migrate with respective phoretic speeds toward the electrodes and to thereby separate into discrete separation zones or bands in the process. The materials in each discrete band can be analyzed for identification and quantification.
However, this process has disadvantages. One disadvantage is that long electrophoretic columns are required to achieve separation, and use of high voltages may be required since different types of particles may resolve into distinctive groups very slowly when their electrophoretic speeds are similar.
Another disadvantage results from electric current which flows through the electrodes at the ends of the electrophoretic element or column. This current, which is limited by using, when possible, lower conductivity column materials, flows the entire length of the column and produces heating of the fluid. A coolant may be required to prevent overheating and evaporation of the fluid and distortion of the separation bands. All these effects generally limit the efficiency and accuracy of the analyzing process. A narrow, high resolution particle separation zone is very difficult to provide and maintain.
A further disadvantage of such prior art laboratory technology is that opposite polarity particles cannot be separated by loading the column at one end.
Because of the high cost and technical limitations, electrokinetic techniques as now used are capable of separating only very small amounts of particles, making the end product very expensive and heretofore impractical for use with commercial quantities of materials. The prior art does not disclose a method or apparatus for a continuous process used for commercial extraction of materials from fluids.
What is needed is a commercial separation system and method using electrokinetic techniques which is useful in purifying fluids and extracting substances from the fluids for the sake of the extracted substance, without the problems of slow performance, extended chamber length, high voltages and resultant heating and evaporation of column fluids.